1. Field of the Invention
This specification relates to a carbon material and a fabrication method thereof, and particularly, to random graphite comprising graphene layers, which are three-dimensionally random in the random graphite, and a fabrication method is thereof using graphene nanoribbons.
2. Background of the Invention
Crystalline structures of graphite are classified according to stacking structures of graphene layers (FIGS. 1 and 2). Since graphite having an AB-stacked structure (hereinafter, referred to as AB graphite) was reported in 1924 [Bernal et al, Proc. Roy. Soc. London, Ser. A 106, 749-773 (1924)], AB graphite (inter-layer spacing is 3.35 Å) has been known as the unique crystalline graphite. Also, the present inventor et al have reported presence of AA′ graphite (inter-layer spacing is 3.43-3.44 Å) [Lee et al, The Journal of Chemical Physics 129, 234709 (2008)].
AA graphite having an AA-stacked structure (theoretical inter-layer spacing is about 3.53 Å) can exist crystallographically. However, AA graphite cannot exist in nature because the AA stacking of graphene layers is unstable energetically, and is temporarily observable when Li atoms are intercalated into AB-stacked graphite.
Meanwhile, turbostratic graphite (inter-layer spacing is 3.41-3.45 Å) has been reported in 1942 [J. Biscoe et al, Journal of Applied Physics 13 (1942) 364], and it is commonly known that turbostratic graphite has a structure that graphene layers are stacked parallel without any structural regularity between the layers. That is, the graphene layers of turbostratic graphite are parallel, but rotated each other (FIG. 2D). Therefore, turbostratic graphite can exhibit a clear and strong (002) peak on an X-Ray diffraction (XRD) pattern.
All types of graphite reported previously, as shown in FIG. 1, are building blocks of parallel stacked graphene layers which are slid (AB, AA and AA′ graphites) or rotated (turbostratic graphite) and show a typical X-ray diffraction (XRD) pattern where a clear and strong (002) peak appears at 2θ=25.9° to 26.6°. This is the reason why graphite is named as an layered material. Meanwhile, amorphous carbon (or amorphous graphite) can be defined as a graphitic material in which graphene layers are not developed (thus, all XRD signals including (200) peaks are). All types of crystalline graphite are typically fabricated at a high temperature over about 2000° C.